[libcamera-devel] [PATCH v6 5/7] libcamera: camera: Validate Request befor queueing it

[Jacopo Mondi]

Validate the Request before proceeding to prepare it at
Camera::queueRequest() time.

For now limit the validation to making sure the Request contains at
least one Stream to capture from.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 src/libcamera/camera.cpp  | 10 ++++++++--
 src/libcamera/request.cpp | 15 ++++++++++++++-
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
index 2d0a80664214..0709047341d7 100644
--- a/src/libcamera/camera.cpp
+++ b/src/libcamera/camera.cpp
@@ -714,8 +714,14 @@ Request *Camera::createRequest()
  * \param[in] request The request to queue to the camera
  *
  * This method queues a \a request allocated with createRequest() to the camera
- * for capture. Once the request has been queued, the camera will notify its
- * completion through the \ref requestCompleted signal.
+ * for capture.
+ *
+ * After allocating the request with createRequest(), the application shall
+ * fill it with at least one capture buffer before queuing it. Requests that
+ * contain no buffers are invalid and are rejected without being queued.
+ *
+ * Once the request has been queued, the camera will notify its completion
+ * through the \ref requestCompleted signal.
  *
  * Ownership of the request is transferred to the camera. It will be deleted
  * automatically after it completes.
diff --git a/src/libcamera/request.cpp b/src/libcamera/request.cpp
index 5e86c8e10128..12a3c5204f24 100644
--- a/src/libcamera/request.cpp
+++ b/src/libcamera/request.cpp
@@ -115,10 +115,23 @@ Buffer *Request::findBuffer(Stream *stream) const
  */
 
 /**
- * \brief Prepare the resources for the completion handler
+ * \brief Prepare and validate the request for the completion handler
+ *
+ * This method prepares resources and validates the request to prepare it for
+ * capture operations.
+ *
+ * Requests that contain no buffers are invalid and are rejected by this method.
+ *
+ * \return 0 on success a negative error code otherwise
+ * \retval -EVINAL The request is invalid
  */
 int Request::prepare()
 {
+	if (!hasPendingBuffers()) {
+		LOG(Request, Error) << "Invalid request due to missing buffers";
+		return -EINVAL;
+	}
+
 	for (auto const &pair : bufferMap_) {
 		Buffer *buffer = pair.second;
 		pending_.insert(buffer);
-- 
2.21.0